Training aids and methods for needle biopsy

ABSTRACT

A training aid for teaching needle biopsy of the human breast. The inventive methods use breast models having lifelike properties providing accurate tactile sensation during palpation of the breast that enable a trainee to learn to locate modeled internal lesions and similar tissues in the breast. These same properties allow learning of tactile sensations indicating relative position and motion of biopsy needles during biopsy needling procedures. To facilitate tactile learning, the breast model includes an opaque skin that blocks the trainee view of a breast cavity containing modeled lesions, ensuring that needling procedures are performed based solely on “feel”. The present invention also includes alternative training methods using a second breast model that is sufficiently transparent to allow viewing of modeled lesions from any relative position. The present invention includes training systems incorporating breast models and viewing stands and methods of training using these aids.

RELATED DOCUMENTS

The present application claims priority from, and is a divisionalapplication of U.S. patent application Ser. No. 09/900,402 filed Jul. 9,2001, now U.S. Pat. No. 6,485,308.

BACKGROUND OF THE INVENTION

The present invention pertains to models and devices used to trainmanual needle biopsy procedures. In particular, the present inventionpertains to manual needle biopsy training methods and systems that usemodels of the human female breast. Breast cancer is among the mostcommon malignant forms of cancer and is a leading cause of death fromcancer among women in the United States. Various methods have evolvedfor breast examination and detection of early stage cancerous growths.Manual breast examination has been found to be a highly effective methodof early breast cancer detection. Tactually accurate breast models havebeen developed to train the palpation techniques used in effectivemanual examination. Training success in breast palpation andself-examination is dependent in part on providing a realistic breastmodel that produces accurate tactile responses in the user. For thisreason, breast models have been designed with lifelike texture andtactile properties.

Lumps or other breast tissue abnormalities revealed by clinicalexamination or other physical examination methods may be indicators ofany of a variety of conditions, some of which are benign and relativelyinconsequential to health. A first step in investigating tissueabnormalities is most often a needle biopsy. In needle biopsy, thebreast is typically first palpated to locate the subject lump. A needleattached to a syringe or a similar suction device is then passed throughthe breast until penetrating the lump. A portion of the suspected tissueis then aspirated and withdrawn for testing. Successful needle biopsyrequires training to assure quick and accurate location of the lump andcertain penetration of the lump by the aspiration needle. Lengthyprobing potentially exposes the patient to trauma and inaccuracy mayresult in false negative test results for failure to aspirate thecorrect tissue. Traditionally, needle biopsy techniques are taught inmedical schools using actual patients. This situation is problematic inview of the majority of patients' unwillingness to cooperate in suchtraining procedures. Consequently, breast models similar to those usedfor breast self-examination have been developed for training needlebiopsy. One such device is provided in U.S. Pat. No. 5,803,746 to Barrieet al.

Because in the clinical situation, the target of a free-hand needlebiopsy is an invisible lesion that must be located by palpation,training devices preferably similarly prevent the trainee from viewingthe target lump. However, this inevitably results in an inefficienttrial-and-error methodology in practice. The Barrie device suffers fromthis weakness. Breast examination can be improved if a trainedinstructor is able to view the trainee's needle and the target withinthe breast model to provide instant comment and corrective feedback on atrainee's technique. However, prior breast models do not provide a meansthat enables an instructor to view a trainee's technique while blockingtrainee visual access to the model. The same elements obscuring thetrainee's vision also obscure the instructor's. Various imaging systemsfor visualizing biopsy needles and phantom lumps within breast modelsbased on such methods as ultrasound and X-ray have been suggested.Examples of these are provided in U.S. Pat. No. 4,493,653 to Robbins etal. and U.S. Pat. No. 5,273,435 to Jacobson. However, the constructionof the breast models in these systems preclude proper palpationtechnique and are very cumbersome. In addition, the viewing operationsof these prior methods interfere with training activities. Effectivepalpation in needle biopsy training demands the same lifelike propertiesin a training model designed to teach the skill of manual breastexamination. However, existing self-examination breast models sufferfrom the same defect as the Barrie devices. For example, U.S. Pat. No.4,134,218, to Adams et al. and U.S. 4,867,686 to Goldstein disclosemodels of a human female breast having lifelike texture and tactileresponse to palpation. These references also teach various methods ofpalpation training including providing transparent breast elements toallow the trainee to observe the subject lumps after palpation to verifytechnique. However, neither Adams nor Goldstein provide a device ormethod enabling a secondary viewer such as an instructor to view atrainee's palpation technique at the time the trainee is palpating themodel.

What is needed is a lifelike breast model including lumps simulatingvarious anomalous tissues and providing an optical path that enables asecond viewer such as an instructor to observe a trainee's needlingtechnique while enabling obscuring the trainee's view of the targettissue.

SUMMARY OF THE INVENTION

The present invention is a training aid for teaching needle biopsy ofthe human breast. It provides breast models having lifelike propertiesproviding accurate tactile sensation during palpation of the breast thatenable a trainee to learn to locate internal lesions and similaranomalous tissues in the breast. These same properties also allowtrainee learning of tactile sensations that indicate relative positionand motion of biopsy needles during biopsy needling procedures. Tofacilitate tactile learning, one breast model of the invention includesan opaque skin that blocks the trainee view of a breast cavitycontaining simulated lesions, ensuring that needling procedures areperformed based solely on “feel”. Such “blinded” breast models aresupported in a position to allow access to the surfaces normallypalpated and penetrated during clinical needling procedures, whileallowing viewing of the breast internal elements by a second party suchas an instructor. In one embodiment, the breast model is supported on atransparent surface of a portable stand. The stand includes opticalelements creating a viewing path from the breast cavity to a secondlocation separate from the trainee. In this way, a trainee may practiceneedling based solely on simulated tactile information while aninstructor observes internal events, enabling real-time comment andinstruction. Because viewing is accomplished by optical light pathwaysand not penetrating electromagnetic radiation (x-ray) or otherpenetrating energy (ultrasound), potential interference of traineeactivities by the viewing operations is eliminated. The models andstands and methods provided allow for palpation and needling of theentire breast model surface and volume without moving the model andwhile providing continuous viewing by second persons. The presentinvention includes training systems incorporating breast models andviewing stands and methods of training incorporating these structuralaids.

The present invention also includes training methods using analternative breast model that is sufficiently transparent to allowdirect viewing of modeled lesions from any relative position. Inpreferred training methods of the invention, this model is used toprovide “error-free” training in which a trainee learns proper tactileindicators of accurate needling techniques. This training mode may beused independent of, or more preferably, preliminary to, training with“blinded” models. The present invention includes training systemsincluding blinded and transparent models and methods of trainingincorporating both. The present devices and methods of presenting andviewing breast models are also used in methods of teaching examinationof breast tissues by palpation without needling.

Particular benefits of the invention include small portable andunpowered embodiments that are easily and cheaply employed in a varietyof circumstances. Other advantages of the invention as described in thefollowing drawings, detailed description, and claims will apparent toone skilled in the art.

DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts one embodiment of the present including a “blinded”breast model supported on a portable stand incorporating a reflectivesurface to establish a viewing path from a cavity within the breastmodel to a location separated from a trainee location.

FIG. 2 depicts a breast model in needling training methods according tothe present invention. A video imaging system transmits an image of thebreast model cavity to a distant location.

FIG. 3 depicts a transparent breast model used in “error-free” trainingaccording to the present invention.

FIG. 4 is a cross section view of a breast model according to thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Proper biopsy needling training requires that a trainee gain the abilityto distinguish and locate specific target lesions by tactile means aloneand the ability to guide a biopsy needle through breast tissue topenetrate these target tissues. Much of the required skills in breastbiopsy needling are the same as those for breast self-examination.However, in addition, tactile sensations of position and motion of thefine needle biopsy needle and needle tip relative to the target tissuemust also be learned. Herein the term “fine needle” and “fine needlebiopsy” refers to devices and procedures in which relatively small gaugeaspirating needles are used to collect small quantities of tissue as istypical in breast tissue biopsy.

To prepare a trainee for performing a needle biopsy on a human, wherethe targeted lesions are always obscured, it is desirable to also trainwith “blinded” models: those which obscure the trainee's view of themodel interior. It is important that the person being trained not beallowed to visually inspect the interior of the model prior to the firstneedling attempt in blinded training. Without prior visual inspection,the person being trained must rely solely upon tactile sensation thatreplicates the procedure with human patients. Training with blindedbreast models consists first of palpating a breast model to locate atarget lesion within the model. The trainee's fingers continue topalpate the breast model to isolate the target while an aspirationneedle is pushed through the model and toward the target. The fingerspalpating the model are able to help locate and guide the needle tip asit moves through the model and into the target. The lifelikecharacteristics of the breast model provide tactile training of theseevents and allow the trainee to accumulate sensory knowledge ofsuccessful technique.

An aspect of the present invention to increase training effectiveness isto give the trainee instructional feedback while practicing blindedneedling to identify successful and unsuccessful technique. Satisfyingthis requirement is impossible with completely opaque models, as theneed for obscuring breast model internal events from the trainee duringneedling practice is incompatible with the instructional requirement ofobtaining and relating such feedback information. In the abovereferenced Goldstein patent, a similar problem with self-examinationtraining is resolved by providing the breast model with an obscured skinand a transparent backing. In Goldstein, after attempted palpation, thetrainee reorients the model to allow trainee viewing through thetransparent backing. However, this mode of operation is not applicableto training needling technique for a variety of reasons. First, anymovement of the breast model easily disrupts the relative positions andorientation of the needle and target. The breast model should be heldstationary during needling training functions. Second, real-timeinstructional feedback during movement of the needle through the breastmodel is not possible using the Goldstein mode.

The present invention resolves this problem with a training method inwhich a breast model with a transparent internal cavity obscures thetrainee view but provides a second viewing path from model internalcavity to a second party, such as an instructor, located away from thetrainee. This is accomplished without moving the model. FIG. 1 depictsan embodiment of the invention providing these features. A portion of ablinded breast model 6 is shown cut away to reveal internal elements.The model 6 has an opaque outer skin 12 and a transparent backing 14 andcavity 13. The model 6 is positioned in use such that the viewing path16 from the trainee positioned at a first relative location 11 to aneedling target 18 in the model cavity 13 is blocked by the skin. Asecond distinct viewing path 20 is provided to a second relativelocation 21. In use, the model 6 is placed on a transparent restrainingsurface 22 of training stand 24. The training stand 24 includes areflective surface 26 configured and oriented to reflect the image ofthe breast internal cavity 13 and events therein to the second location21. The viewing paths are oriented such that the first location 11 andsecond location 21 are sufficiently separated that a trainee at thefirst location 11 is unable to view the image provided by the secondviewing path 20. For example, the breast model 6 may be positioned at ona stand at standard desk height and a trainee instructed to work in astanding position such that the trainee's eyes will naturally berelatively above the breast model 6 and blocked by the opaque skin 12.The second viewing path 20 then is oriented at an angle from the firstlocation 11 to eliminate the opportunity of the trainee viewing theimage projected along the second viewing path 20. An instructor or othersecond party positioned at the second location 21 is able to view theinternal cavity of the breast model, as well as any events therein,while the trainee's view is obscured. During this blinded model mode oftraining of the present invention, an instructor, or other person,observes the needling observation as it occurs and provides real-timefeedback to the trainee regarding the ongoing needling procedure. Inthis way, a trainee may attempt a palpation or needling movement whileblinded from the movements and immediately receive feedback commentsregarding the consequences or success of that event. Any traineecorrective efforts are still blinded.

In an alternative embodiment shown in FIG. 2, the viewing path to asecond location is formed in part by an image transmitting system suchas a video-capable camera 40 directed through a transparent glass top 28of a stand 24 which supports a blinded breast model 6. The camera 40 isfunctionally connected to a distant monitor 42 on which is displayed animage 44 received by the camera 40. In this manner the view of the modelcavity and events therein may be transmitted to any remote location. Anadvantage of this embodiment is the ease with which additional personsmay view the training events. The monitor may be placed to allow severalpeople to observe the received image. This may be used to provide anadditional training aspect by allowing other additional trainees to viewprocedures as they occur. A light source 46 is provided and positionedto illuminate the breast model internal cavity 13 to enhance viewing. Inthe figure, the model is cutaway to show an aspiration needle 50 isshown as in use penetrating the model skin 12 and directed to a target18 while the breast model 6 is palpated by a trainee's finger 52.

One benefit of the embodiments exemplified in FIGS. 1 and 2 are theirsmall size and simplicity which encourage their availability and use.The training stand 24 must support the transparent restraining surface22 relative to the elements of the secondary viewing path, whether areflective surface or a video camera. The transparent restrainingsurface 22 may be provided by a glass top 28 as shown or othersubstantially transparent supporting means such as transparent plastic.The restraining surface 22 must be of sufficient size and rigidity tosupporting a breast model during needling operation. A stand 24 havingrestraining surface width dimensions of six inches (15 cm) is sufficientto support a typical breast model. The height of the stand is dependentonly on the construction and elements of the secondary viewing path, andmay be as small as twelve inches (30 cm) or less when used with compactoptical elements such as small video cameras or a fixed mirror. Thestand includes a base 53 for retaining the stand on a horizontal surfacesuch as a tabletop. The base may incorporate legs or equivalentstructures. A training stand as just described is small enough to beeasily stored, transported and handled by one person in a variety ofsituations. In particular, such a system and stand is of a size to becontained in luggage of a size meeting the “carry-on” standards ofcommercial airlines, providing ease of use in a variety of locations.Using a secondary viewing path incorporating a physical mirror, thestand is portable and may be used in locations without power sources.Alternative reflective surfaces consisting of a mirror having at leastone axis of rotation to allow for manipulation of the secondary viewingpath are also contemplated. Design particulars of this feature aregenerally known to those skilled in the art. In general, the stand 24should allow easy access by a trainee to a breast model positioned onthe stand. Because the entire volume of the breast model may need bepalpated, and from various angles, it is important that the stand, andall other structures, be distant from the sides of the stand and breastmodel so positioned.

One mode of the present invention introduces “error free” practicetraining in which a trainee is initially allowed to practice in anon-blinded mode before proceeding to the blinded mode. This isaccomplished by providing a breast model that is fully transparent tothe trainee. One embodiment of this transparent model 8 is shown inFIGS. 3 and 4. The fully transparent breast model 8 includes atransparent outer skin 32. The model 8 also has a transparent backing14, internal cavity 13 and targets 18 in the same fashion as the blindedmodel 6. The objective of this mode and model is to provide the traineea clear viewing path to the model targets. In this mode of training thetrainee practices needle insertion and penetration techniques whilebeing able to watch, and feel, the needle position and motion throughthe transparent breast model 8 and into the targets 18. At the sametime, the trainee is able to relate the tactile feedback of thetrainee's palpations with the resulting effect on the needle motion andtarget. This mode allows the trainee to experience successful“error-free” needling and build a base of knowledge of the proper feelof successful needle manipulation. So called “error-free” training isdistinguished here from training using “blinded” models in which theneedle within the model and the target is obscured from the trainee'svision. Error-free training can reduce the training inefficiencypossible with trial-and-error blinded training. Preferably trainees areprovided error-free training prior to training with blinded models.However, benefits are gained independently with each model and mode oftraining.

While each of the present breast models and the training stands provideindependent benefits to fine needle aspiration training, they are moreeffectively used as an integrated system. The present invention includessystems for training fine needle biopsies of the human breast. Oneembodiment of such systems includes both 1) a blinded breast modelhaving an obscuring skin and a transparent backing and internal cavitysimulated target lesions, 2) a viewing stand providing a breast modelsupporting means and secondary viewing path. A more preferred systemproviding both error-free and blinded modes of training includes allof 1) a fully transparent breast model including target lesions, 2) ablinded breast model having an obscuring skin and a transparent backingand internal cavity and targets and 3) a viewing stand providing abreast model supporting means and secondary viewing path. A preferredtraining method using this preferred system comprises the steps of 1)error-free training in which trainees attempt needling techniques with afully transparent breast model having various sized and positionedlumps, followed by 2) blinded training with a blinded breast modelhaving various lumps that differ from those in the error-free model.

To properly instruct needling techniques for needle aspiration of breasttissues, both transparent models and blinded models should besubstantially lifelike. The models should provide lifelike shape andfeatures and correct tactile response so that needling techniques willbe learned through practice with realistic tactile stimuli. The modelsshould provide accurate tactile distinction of internal elements toallow the user to train tactile identification of subject anomaloustissues. It is preferred that models be available in several sizes andvarying degrees of firmness to enable training for a representativecross-section of the female population. Except for the obscuring ortransparent nature of their respective skins, the two models discussedabove may be constructed in like fashion. Except where specificallyindicated otherwise, the following construction details apply equally toblinded and fully transparent models. The models 6, 8 are substantiallyhemispherical in shape. The skin is an elastomeric membrane simulatinghuman skin. In the error-free breast model 8 the skin 32 is transparent,while the elastomeric membrane forming the skin 12 of the blinded model6 (FIGS. 1, 2) includes an opaquing material. The hemisphere of skin 12is enclosed by backing 14 formed of a like elastomeric membrane. Boththe skin 12 and backing 14 may be made of any of a variety of materialsproviding skin-simulating properties including, but not limited to,polyvinyl chloride, polyurethane or elastomeric silicone resin polymers.Suitable elastomeric silicone resin polymers are commercially availablefrom General Electric Company and Dow Corning Corporation, among others.A skin 12 having a hardness less than durometer 20 ( Shore 00- ASTM2240), and more preferably in the range of durometer 10 to 20, providesthe desired lifelike properties. The material used to form the skin 12of the transparent model 8 and the backing 14 must be transparent andshould provide good optical clarity to allow for visual inspection ofthe internal cavity of the models. The material(s) used to form thebacking 14 and the skin 12, 32 should also be of a sufficient thicknessand strength to withstand the repeated pressures exerted on the modelduring palpation and repeated penetrations by aspiration needles,although the skin should not be so thick as to detract from therealistic feeling thereof A skin thickness in the range of 0.0025 to0.005 inches (0.0063 to 0.013 cm) has been found acceptable. Due to themethods of construction, skin thickness is difficult to control and willvary over the area of a single model. A flange portion 56 of the backingextends outward from the skin and is not critical but provided for easeof handling and to help retain the shape of the model. Between the skin12,32 and backing 14 the internal cavity 13 is filled with a transparentsimulated adipose tissue medium 54 (not distinctly depicted in FIGS. 1and 2 for clarity). The targets 18 are configured to simulate one ormore tumors, cysts, or other subject tissues and are suspended withinthe medium 54. Simulation is principally effected by providing materialhaving density tactilely differentiating the lumps from the surroundingmedium. The targets are preferably opaque in all models. It will beappreciated by one skilled in the medical arts that real breast tumorsare located in various locations in the human female breast and areprone to feel as though they are relatively fixed in position or,alternatively, free floating. Accordingly, the feel of such tumors andthe difficulty in locating and such tumors by palpation and directing aneedle to them varies. For this reason, it is desirable to locate thetargets 18 in varying locations in the models, and variously indifferent models, according to the present invention. Although thetarget constructions specified herein do not provide for actualaspiration into an aspirating needle, other targets capable ofaspiration may be incorporated to add a training element. Textureinducing elements such as silica may be added to the media to enhance arealistic feel. General methods of constructing the above breast modelfeatures are provided in U.S. Pat. No. 4,134,218, to Adams et al. andU.S. Pat. No. 4,867,686 to Goldstein, the disclosures of which areincorporated herein by reference and may be followed except as specifieddistinctly herein. The medium 54 is formed according to the constructionof Goldstein for means simulating adipose tissue. It is not critical touse the particular materials suggested for forming the skin 12, backing14, medium 54 and target 18. Rather, the models 6, 8 should have thecomplex feel of adipose tissue within a human female breast and thetargets 18 should accurately simulate the feel of real tumors.

Because needle biopsies introduce the element of penetration of thebreast and breast tissues, effective models for biopsy training haveadditional requirements over self examination models. In order toprovide lifelike feel, breast models are often filled with materialshaving almost fluid-like properties, i.e., the simulated adipose tissuemedium. Penetration of the breast model skin may potentially allow thesematerials to leak out through the penetration when the needle isremoved. The breast model outer layer or skin must be sufficientlyself-sealing with respect to the particular internal materials toprevent leakage. The constructions taught by Goldstein have been foundto be acceptably self-sealing with the skin thicknesses specifiedherein. When a biopsy needle is forced through the epidermis andpenetrates the breast tissue in an actual biopsy procedure, theclinician handling the procedure feels the resistive forces of theepidermal wall and breast tissue on the needle and these senses effectthe clinician's ability and success in distinguishing and penetratingtarget tissues. The breast models described herein substantially providethis tactile feedback to a trainee.

The preceding details are provided for example only. Other variations ofthe claimed inventive concepts will be obvious to those skilled in theart. For example, the preceding discussion expressly discusses “fineneedle” techniques and procedures. It will be clear that the samemethods are applicable to clinical techniques involving larger boreneedles including what is commonly termed “large-core” needles andassociated large-core needle biopsy procedures as well as otherfree-hand needling procedures for biopsy of tissue. Adaptation orincorporation of alternative devices and materials, present and futureis also contemplated. The intended scope of the invention is defined bythe following claims.

I claim:
 1. A method of training examination of tissues within the humanbreast, comprising: positioning a lifelike human breast model to allowpalpation of a breast model cavity while preventing viewing of the modelcavity; palpating a lump within the cavity, by a trainee, while enablinga second person to observe the cavity.
 2. The method of claim 1, andfurther comprising: providing information to the trainee regardingviewed events within the breast model.
 3. The method of claim 1, andfurther comprising: needling of tissues inside the breast model by thetrainee while preventing the trainee's viewing the model cavity.
 4. Themethod of claim 3, and further comprising: needling of tissues inside asecond breast model by the trainee while allowing the trainee to observethe inside of the second breast model.
 5. A method of trainingexamination of tissues within the human breast, comprising: palpating abreast model by a trainee, while preventing the trainee from viewing amodel cavity; while projecting an image of at least a portion of thecavity to a location separated from the trainee.
 6. The method of claim5, and further comprising: forming a tactilely accurate opaque breastmodel; supporting the model to allow palpation.
 7. The method of claim5, wherein: the step of projecting an image includes projecting an imageonto an electronic monitor.
 8. The method of claim 5, furthercomprising: palpating a transparent breast model by the trainee.